Three-phase electric power may be used as a method of alternating current electric power transmission. A three-phase system may be more economical than others because it may use less conductor material to transmit electric power than equivalent single-phase or two-phase systems at the same voltage. In a three-phase system, three conductors carry three alternating currents of the same frequency, which reach their instantaneous peak values at different times.
The currents of each phase may cancel each other out and sum to zero in the case of a linear balanced load. Power transfer to a linear balanced load may be constant. However, in some instances, a load may not be naturally balanced. In such instances, it may be advantageous to balance the loads, as overloading one phase over another can increase power consumption fees and call for more infrastructure capacity than a balanced load would.
For instance, in the case of a datacenter, individual computing devices (e.g., servers) may use only one or two of the three phases. Even if the same amount of servers are put on every phase, differing server loads may cause an unbalance in the system.
Some previous approaches to load balancing multi-phase and/or multi-module power supplies have employed active load balancing. For example, a multi-phase power supply can use a current sensor including a sensor inductor winding in parallel with a filter inductor winding at an output of each phase for sensing the phase currents and balancing the current by adjusting the duty cycle of each phase through feedback control. However, such active systems may use power and may be expensive to implement in terms of design, deployment, and use of space within a datacenter and/or various components thereof.